Coatings and methods for particle reduction

ABSTRACT

The present disclosure relates to high purity apparati, e.g., magnetic hard disk drives, and more specifically, to coatings for particle reduction of surfaces of such apparati. The provided coatings include thin polymer coatings with reactive pendant groups having crosslinking functionality and ability to anchor to substrate surfaces to suppress particle shedding from substrate surfaces. Provided is a substrate that includes a coating on at least a portion of the substrate that comprises a fluorinated acrylate random copolymer. Methods of reducing particulate contamination are also provided.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/016,050, filed Dec. 21, 2007, which is incorporated herein byreference in its entirety.

FIELD

The present disclosure relates to high purity apparati, e.g., magnetichard disk drives, and more specifically, to coatings for particlereduction in such apparati.

BACKGROUND

In magnetic disk drives and other high purity applications, particlecontamination can cause a host of failure mechanisms. In theseapplications, it is highly desirable to minimize particles present inmanufacturing and during application. Magnetic disk drives typicallycomprise a number of precisely dimensioned operating parts, e.g.,spacers, disk clamps, e-blocks, cover plates, base plates, actuators,voice coils, voice coil plates, etc. These components can all bepotential sources of particles. During drive operation, the headtypically flies over the media at a spacing of about 100 Å. This spacingis decreasing with increasing areal density, making the reduction andprevention of particle generation ever more critical. Particles at thehead disk interface can cause thermal asperities, high fly writes, andhead crashes; any of these are detrimental to performance of a diskdrive.

U.S. Pat. Publ. No. 2003/0223154 (Yao) discloses prevention of particlegeneration by encapsulation with a coating “made of a soft and tenaciousmaterial, such as gold, platinum, epoxy resin, etc.” U.S. Pat. Publ. No.2002/0093766 (Wachtler) discloses the use of adhesive-backed heatshrinkable conformal films to protect against particle generation. U.S.Pat. No. 6,671,132 (Crane et al.) discloses the use of metal orpolymeric coatings. U.S. Pat. No. 7,035,055 (Kikkawa et al.) disclosesthe use of resin coatings. U.S. Pat. No. 6,903,861 (Huha et al.)discloses the use of certain polymer coatings as an encapsulant formicroactuator components. PCT Publ. No. WO 2006/074079 (Kehren et al.)discloses the use of fluoropolymers comprising reactive pendant groupsfor particle suppression coatings.

Particles within hard drive assemblies can lead to friction andlocalized hot spots, which in turn can lead to failure of the hard driveand loss of the data magnetically encoded with it. One approach to thisissue has been use of electroplated nickel as a particle suppressioncoating on the cover to the hard drive. However, nickel has tripled inprice between about 2001 and about 2006. Also, the requirement toelectroplate the hard drive cover leads to more steps in assembly thancoating and curing of a low surface energy coating onto the hard driveassemblies, the electroplating process entails use of potentiallyhazardous materials, and particles shed from such coated parts are veryhard, i.e., nickel particles, that can readily cause significant damageto the media and read/write head(s).

E-coats or electophoretically-deposited coatings are also used asparticle suppression coatings but it can be difficult to obtain uniformcoatings (necessitating some post coating machining). In addition,outgassing related to uncured monomers or absorption of hydrocarbonsinto the coatings that later outgas into the drive is encountered.

SUMMARY

The need exists for cheaper, more conveniently applied, high performanceparticle reduction coatings. Provided are improved coatings for particlesuppression from substrates with oxide surfaces such as metals, e.g.,aluminum, copper, stainless steel, etc., plastics, glass, ceramics,silicon, etc. The provided coatings can be applied with simpletechniques (e.g., dip coating and thermal cure), exhibit thermalstability, can be formed in substantially uniform thin (e.g., from about0.1 to about 5.0 microns) layers over complex substrate topographies.The coatings are clean (i.e., low outgassing, low extractable ions), areresistant to typical cleaning processes (e.g., aqueous and solvent-basedcleaning solutions with or without ultrasonic treatment), areenvironmentally benign (i.e., delivered with solvents such as segregatedhydrofluoroethers), have a good safety profile, and provide relativelysuperior cost-to-benefit performance as compared to the current industrymethod of nickel coating. The provided coatings may also providecorrosion protection.

The provided coatings comprise a thin polymer coating with reactivependant groups having crosslinking functionality and superior ability toanchor to the substrate surface to suppress particle shedding fromsubstrate surfaces. These particles can be from the substrate materialor materials left over from processing and/or incomplete cleaning. Thiscoating, in essence, forms a net over the surface of the substrateholding in particles, which otherwise could shed from the substrate.

In one aspect, provided is a substrate that includes a coating on atleast a portion of said substrate wherein said coating comprises afluorinated acrylate random copolymer having the following generalformula:

XA_(w)B_(x)C_(y)D_(z)T

where X is the initiator residue or hydrogen, A represents units derivedfrom one or more divalent fluorochemical acrylate monomers, B representsunits derived from one or more divalent acrylate monomers with afunctional group, C represents units derived from one or morenon-fluorinated divalent acrylate monomers with a hydrocarbon group, Drepresents units derived from one or more curatives, T represents afunctional terminal group or X defined as above, w is an integer from 1up to about 200, x is an integer from 1 up to about 300, y is an integerfrom 1 up to about 100, and z is an integer from 0 up to about 30, andwherein C is selected from the group consisting of monomers whosehomopolymer has a glass transition temperature of less than or equal to20° C.

In another aspect, provided is a method of reducing particulatecontamination that includes providing at least one of a hard disk driveassembly, a MEMS device, a process equipment for electronics or aprinted circuit card assembly, and applying a coating on at least aportion of the assembly of at least one of a hard disk drive assembly, aMEMS device, a process equipment for electronics or a printed circuitcard assembly, wherein the coating comprises a fluorinated acrylaterandom copolymer having the following general formula:

XA_(a)B_(b)C_(c)D_(d)T_(e)

where X is the initiator residue or hydrogen, A represents units derivedfrom one or more divalent fluorochemical acrylate monomers, B representsunits derived from one or more divalent acrylate monomers with afunctional group, C represents units derived from one or morenon-fluorinated divalent acrylate monomers with a hydrocarbon group, Drepresents units derived from one or more curatives, T represents afunctional terminal group or X defined as above, a+b+c+d+e=1,0.20≦a≦0.90, 0.05≦b≦0.25, 0.05≦c≦0.65, 0.0005≦d≦0.03, and 0.0025≦e≦0.20,wherein a, b, c, d, and e are weight percentages of A, B, C, D, and T,respectively, and wherein C is selected from the group consisting ofmonomers whose homopolymer has a glass transition temperature of lessthan or equal to 20° C.

In brief summary, the provided substrates, coatings, and methodscomprise the reaction product of specified fluorochemical monomers andhydrocarbon monomers wherein the coating is at least partially cured insitu on the substrate. When at least partially cured in place, suchcoatings can provide surprisingly good performance as particle reductioncoatings on substrates. Incorporation of hydrocarbon segments into thebackbone of the copolymer has been surprisingly found to improve theparticle suppression performance of the subject coatings and increasethe resistance of resultant coatings to cleaning processes, particularlythose processes used on electronics components such as ultrasoniccleaning processes. The provided coatings offer many advantagesincluding but not limited to the ease of obtaining thin, uniform coatingon complex surfaces, good safety and environmental properties, andresultant coatings that exhibit low surface energy. The providedcoatings provides particle suppression coatings that are of relativelylower cost, provide improved resistance to cleaning, improved particlesuppression performance. Improved handling and abrasion resistance hasalso been observed.

As used herein, “acrylate” can also be understood to mean“methacyrlate”; and “pendant” refers to end groups and side groups.

GLOSSARY

As used herein the following abbreviations have the indicated meanings:

-   -   A174 is 3-trimethoxysilane propyl methacrylate;    -   AA is acrylic acid;    -   BA is butyl acrylate;    -   BuMA is butyl methacrylate;    -   EHA is 2-ethyl hexyl acrylate;    -   FBSEA is C₄F₉SO₂N(CH₃)CH₂CH₂OC(O)CH═CH₂ which can be made by the        procedure of Examples 2A and 2B of PCT Application No.        WO01/30873A (Savu et al.) which is incorporated herein by        reference in its entirety;    -   FBSEMA is C₄F₉SO₂N(CH₃)CH₂CH₂OC(O)C(CH3)═CH₂ which can be made        by the procedure as Examples 2A and 2B of PCT Application No.        WO01/30873A;    -   HFE is hydrofluoroether;    -   HFPOMA is hexafluoroproplyene oxide methacrylate which can be        made by the procedure of Preparative Example 3 of U.S. Pat. No.        6,995,222 (Buckanin et al.) which is incorporated herein by        reference in its entirety;    -   IOA is iso-octyl acrylate;    -   MMA is methylmethacrylate;    -   MPTS is 3-mercaptopropyl trimethoxysilane; and    -   PFPHMA is heptafluorobutyl methacrylate (i.e.,        CF₃CF₂CF₂CH₂OC(O)C(CH3)=CH₂) which can be made by the procedure        described in PCT Application No. WO 02/16517 (Savu et al.) at        page 15, lines 8-29, which is incorporated herein by reference        in its entirety.

The above summary is not intended to describe each disclosed embodimentof every implementation of the present invention. The brief descriptionof the drawing and the detailed description which follows moreparticularly exemplify illustrative embodiments.

DETAILED DESCRIPTION

In the following description, it is to be understood that otherembodiments are contemplated and may be made without departing from thescope or spirit of the present invention. The following detaileddescription, therefore, is not to be taken in a limiting sense.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

In one embodiment, coatings of the invention comprise fluorinatedacrylate copolymer compounds of the following general formula:

XA_(w)B_(x)C_(y)D_(z)T

where X represents the residue of an initiator or hydrogen, A representsunits derived from one or more divalent fluorochemical acrylatemonomers, B represents units derived from one or more divalent acrylatemonomers with a functional group, C represents units derived from one ormore non-fluorinated divalent acrylate monomers with a hydrocarbon group(preferably BA), D represents units derived from one or more curatives,e.g., acidic acrylate (preferably acrylic acid), and T represents afunctional terminal group or X as described above. The curative, D, maybe present in the copolymer or may be provided as an external catalyst.The copolymer can be random, i.e., the order of the A, B, C and Dsegments is random though it will be understood that some local portionsmay exhibit a more block copolymer structure. The number averagemolecular weight of the copolymer is from about 500 to about 50,000,preferably from about 1000 to about 10,000.

The values w, x, y and z are as follows: w is an integer from 1 up toabout 200, x is an integer from 1 up to about 300, y is an integer from1 up to about 100, and z is an integer from 0 up to about 30 wherein theratio of z:(x+1) is from 0 up to less than about 0.3. The ratio of thesum of (w+y):x is greater than about 1 and less than about 20,preferably greater than about 2 and less than about 8. The ratio of y:wis typically from 0 up to less than 7, preferably greater than about 0.2and less than about 1.5. This ratio is also limited by solubility of theresultant copolymer. If the ratio is too high, the resultant copolymerwill no longer be sufficiently soluble in HFE making such embodimentsmore difficult to use. Co-solvents can help extend this ratio. Atrelatively higher ratios, the resultant coating may subject to increasedtendency to absorb and later emit, e.g., outgas, organic contaminants.

A can be derived from fluorinated acrylic monomers, preferably FBSEA,PFPHMA, and HFPOMA. Other suitable fluorinated monomers may be usedinstead or in addition to the preferred materials listed here ifdesired. In some embodiments, A is a unit derived from a monomer havingthe formula,

R^(f)QOC(═O)C(R)═CH₂

where R^(f) is a perfluoroalkyl or perfluoropolyether group having 1 to30 carbon atoms, Q is a divalent linking group selected from the groupconsisting of —(CH₂)_(n)—, —(CH₂)_(n)— SO₂N(R′)—, and—(CH₂)_(n)N(R″)C(═O)—, where R′ is —C_(n)H_((2n+1)), n is an integerfrom 1 to 6, and R″ is hydrogen or CH₃.

B can derived from a functionalized divalent acrylate monomer, e.g.,silane-containing propyl acrylate or ethyl acrylate, epoxy acrylate, ora divalent urethane acrylate. A preferred example is A174. B can serveto provide crosslinking between polymers as well as bonding to thesubstrate.

The hydrocarbon segments, i.e., C in the formula above, impart improvedsoftness to the resultant copolymer making the resultant particlesuppression coating more resistant to thermal stresses and mechanicalstresses. The C segment can be derived from monomers that are preferablythose whose homopolymer has a low T_(g), i.e., less than or equal toabout 20° C. Illustrative examples of monomers suitable for use as Csegments suitable for use in the present invention include methylacrylate (CH₂═CHCOOCH₃, T_(g)=9 to 15° C.), butyl acrylate(CH₂═CHCOOC₄H₉, T_(g)=−54° C. as reported in 4th Edition PolymerHandbook, L. E. Nielsen, Mechanical Properties of Polymers, Reinhold,N.Y., 1962), isooctyl acrylate (T_(g)=−45° C. as reported in 4th EditionPolymer Handbook, A. R. Monahan, J. Polym. Sci. A-1, 4, 2381 (1966), andethyl hexyl acrylate (T_(g)=−50° C. as reported in 4th Edition PolymerHandbook, A. R. Monahan, J. Polym. Sci. A-1, 4, 2381 (1966), and butylmethacrylate (T_(g)=20° C. as reported in Encyclopedia Polymer Scienceand Technology, Vol. 3, p. 251, John Wiley and Sons Publishers). The Csegment preferably does not contain a reactive group. The C segment alsopreferably exhibits effective solubility in fluorocarbon solvents whichare used in the preparation process of the random acrylic copolymerbefore cross-linking. Typically, HFEs are preferred for this purpose astheir use offers a number of processing and environmental advantages aswell as allows for thin uniform coatings even on complex surfaces. Ifdesired, blends of fluorocarbons solvents with organic solvents (i.e.ethyl acetate, IPA, etc.) can be used to extend the range of C monomersegments that can be used.

To improve the curing performance, the polymer precursor composition mayoptionally include one or more curatives, i.e., D in the formula.Illustrative examples include acidic acrylates, e.g., acrylic acid,methacrylic acid, carboxy propyl acrylate, carboxylic acids, andsulfonic acids, e.g., 2-acrylamido-2-methylpropane sulfonic acid. Thecurative may be fluorinated or not as desired. Use of a curative isgenerally preferred; because it is incorporated into the reactionproduct, there is typically no outgassing.

When D is 0, the curing rate of the coating material may be enhanced asdesired by addition of effective amounts of suitable catalyst dependingupon the selection of reactive groups, parameters of the substrate,desired processing conditions, etc. For example, for coatings made usinga perfluoropolyether silanes may be catalyzed using such agents asKRYTOX 157 FSL perfluoropolyalkylether carboxylic acid from DuPont.

T can be a functionalized terminal group, e.g., a silane. T can bederived from a chain transfer agent. A preferred agent is MPTS.

A free radical initiator is generally used to initiate thepolymerization or oligomerization reaction. Commonly known free-radicalinitiators can be used and examples thereof include azo compounds, suchas azobisisobutyronitrile (AIBN), azo-2-cyanovaleric acid and the like,hydroperoxides such as cumene, t-butyl and t-amyl hydroperoxide, dialkylperoxides such as di-t-butyl and dicumylperoxide, peroxyesters such ast-butyl peroctoate, t-butylperbenzoate and di-t-butylperoxy phthalate,diacylperoxides such as benzoyl peroxide and lauroyl peroxide.Additionally, it is contemplated that compounds that generate freeradicals or acidic and radical species upon exposure to actinicradiation can also be used to initiate the polymerization reaction.Examples of such species include IRGACURE 651 and DAROCUR 1173 availablefrom Ciba.

Preferably, the substrate and coating are selected such that the coatingcan be anchored to the substrate surface via covalent bonding. Thereactive pendant groups, i.e., silane groups, on the molecule cancontribute to this desired bonding performance. In addition, while we donot wish to be bound by this theory, it is believed that the coating mayprovide superior corrosion protection as the silane groups react withbonds sites on the substrate that would otherwise be susceptible tocorrosion reactions.

The coating thickness may be on the order of or substantially smallerthan the size of the particles being held on the substrate, e.g.,coating thickness in the range of from about 0.01 to about 1.0 micron ascompared to an average particle size in the range of from about 0.1 tomore than 5 microns. In the presence of water, alkoxy groups can reactwith the functional groups of the B and/or T unit to form a silanolgroup on the polymer. The silanol group can react with other silanolgroups, thus crosslinking the polymer, and in the case of oxide surfaces(e.g., aluminum, copper, silicon, ceramic materials, etc.), covalentlybonding the polymer to the surface.

An illustrative method of coating substrates in accordance with theinvention is as follows:

a) mixing the precursor materials described above, i.e., initiator,acrylates, curative (if any), etc. in a suitable solvent, e.g., ahydrofluoroether and reacting the precursor materials to yield a coatingcomposition containing the random copolymer;

b) applying the coating composition to desired portions of a substrate(any suitable coating technique can be used);

c) evaporating the solvent to leave the random copolymer on thesubstrate (an advantage of HFE solvents is that they will evaporatequickly);

d) elevating the temperature, e.g., to from about 100° C. to about 150°C., to cause the coating to cross link and build adhesion to thesubstrate.

In some applications it is preferred to use a two stage curing process.In this case, step d) is divided into two steps. In the first step, thecoated substrate is cured so that the coating is tack-free, but hasremaining reactive pendant groups. The coated substrate may then be runthrough additional processing. This may include addition of tapes,labels, epoxies or “form-in-place-gaskets”. In the second step, thecoated substrate is completely cured. This two stage cure can improvethe adhesion of tapes, labels, epoxies and “form-in-place-gaskets. Thecuring in each step is preferably done at elevated temperatures. It hasalso been observed that superior results are typically achieved if thecoating is cured by heating at a relatively lower temperature for longertime than if cured by heating at a higher temperature for shorter time,e.g., at about 120° C. rather than about 150° C. Subsequent adhesion toarticles with coatings of the invention can be improved by wiping with afluorochemical solvent shortly before bonding.

In another embodiment, provided is a method of reducing particulatecontamination that includes providing at least one of a hard disk driveassembly, a MEMS device, a process equipment for electronics or aprinted circuit card assembly; and applying a coating on at least aportion of the assembly of at least one of a hard disk drive assembly, aMEMS device, a process equipment for electronics or a printed circuitcard assembly, wherein the coating comprises a fluorinated acrylaterandom copolymer having the following general formula:

XA_(a)B_(b)C_(c)D_(d)T_(e)

where X is the initiator residue or hydrogen, A represents units derivedfrom one or more divalent fluorochemical acrylate monomers, B representsunits derived from one or more divalent acrylate monomers with afunctional group, C represents units derived from one or morenon-fluorinated divalent acrylate monomers with a hydrocarbon group, Drepresents units derived from one or more curatives, T represents afunctional terminal group or X defined as above, a+b+c+d+e=1;0.20≦a≦0.90, 0.05≦b≦0.25, 0.05≦c≦0.65, 0.0005≦d≦0.03, and 0.0025≦e≦0.20,wherein a, b, c, d, and e are weight percentages of A, B, C, D, and T,respectively, and wherein C is selected from the group consisting ofmonomers whose homopolymer has a glass transition temperature of lessthan or equal to 20° C. In some preferred embodiments, 0.40≦a≦0.80 and0.05≦c≦0.25.

The provided coatings can be of use in a variety of high purityapplications such in hard disk drive assemblies including suchcomponents as spacers, disk clamps, e-blocks, cover plates, base plates,microactuators, sliders, voice coils, voice coil plates etc. Thesecomponents are all potential sources of particles in finished disk drivesystems. Coatings of the invention may also be used to reduce particleshedding for MEMS (Micro Electrical-Mechanical Systems), high purityprocessing (coating process equipment to reduce potentialcontamination), and semiconductor processing applications, e.g., surfacemount components on a printed circuit card assembly. In addition,coatings of the invention have been observed to impart anti-smudge andeasy clean performance to substrates to which they are applied.

Objects and advantages of this invention are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention.

EXAMPLES

Test Substrates: Aluminum (Al5052 H32) and stainless steel (SS304)sheets were purchased from M. Vincent & Associates of Minneapolis, Minn.and cut into test coupons approximately 51 mm×25 mm×1.6 mm in size foraluminum and 51 mm×25 mm×0.4 mm for stainless steel.

Cleaning Method 1: Prior to applying the coating, the substrates werecleaned by wipe cleaning using isopropyl alcohol (from EMD Chemicals ofGibbstown, N.J., part number PX1835P-4) and VWR SPEC-WIPE 7 Wipers (fromVWR International, LLC of West Chester, Pa.).

Cleaning Method 2: Prior to coating, substrates were cleaned in twostages by vapor degreasing. In the first stage, a two sump vapordegreaser, model number 1012, obtained from Ultra-Kool, Inc. ofGilbertsville, Pa. was used to clean with 3M Novec HFE-72DA (from 3M Co.of St. Paul, Minn.) using the following parameters:

30 seconds initial vapor rinse,

300 seconds in the rinse sump with 40 kHz ultrasonics, and

30 seconds final vapor rinse.

In the second stage, a two sump vapor degreaser, model number LAB-KLEEN612 Degreasing System, from Unique Equipment Corporation of Montrose,Calif. was used to clean with an azeotrope of 89% (by weight) 3M NOVEC7300 Engineered Fluid (from 3M Co. of St. Paul, Minn.) and 11% DOWANOLPM Propylene Glycol Methyl Ether (from Dow Chemical Company of Midland,Mich.) using the following parameters:

30 seconds initial vapor rinse,

300 seconds in the rinse sump with 40 kHz ultrasonics, and

30 seconds final vapor rinse.

Coating Method: The coating was applied to the substrate by dip coating.

Determination of Percent Cure: A solvent extraction test method was usedto determine if the coating crosslinked and adhered to the substrate.Prior to coating, the mass of the substrate was recorded (M_(BC)). Themass of the substrate after coating and curing was also recorded(M_(AC)). The substrate was then immersed in 3M™ NOVEC 7100 EngineeringFluid (methoxy-nonafluorobutane (C₄F₉OCH₃) from 3M Company of SaintPaul, Minn.) for 2 minutes. During this time the substrate was gentlyswirled in the solution. The mass of the substrate after solventextraction was then recorded (M_(SE)). The extent of curing was thendetermined by the following calculation:

Percent Cure=[(M _(SE) −M _(BC))/(M _(AC) −M _(BC))]*100

This test was typically run on three substrate pieces for repeatability.

Particle Extraction Method: Liquid particle counter (LPC) extraction wasused to determine the tendency of a substrate to shed particles. Thetest method used is based on IDEMA Microcontamination Standard M9-98.

All testing occurred in a clean hood with a class 100 environment. Thewater used throughout the testing was 18.2 MΩ (supplied using a NANOpureDIAMOND Analytical Ultrapure Water System from Barnstead Internationalof Dubuque, Iowa, part number D11901) and filtered with an EMFLON II,0.2 micron absolute filter (from Pall Corporation of East Hills, N.Y.,part number DFA4001V002PV).

The test apparatus consisted of a 600 mL beaker (from VWR International,LLC of West Chester, Pa.) fixtured in an ultrasonic bath (from CrestUltrasonics Corporation of Trenton, N.J., part number 6HT-1014-6T). Theultrasonics to the tank was supplied by a generator (from CrestUltrasonics Corporation of Trenton, N.J., part number 6HT-1014-6W). Thesubstrates to be tested were suspended in the beaker using a 28 gauge,solderable polyurethane stator wire (from MWS Wire Industries ofWestlake Village, Calif., part number 28 SPN-155 RED) such that theneither the wire nor the substrate contact the beaker. The particlelevels in the water were measured using an 8103 syringe sampling system(from Hach Ultra Analytics of Grants Pass, Oreg.).

For the testing, the beaker was filled with 500 mL of water. With thestator wire in the fluid, the beaker subjected to 30 seconds of 68 kHzultrasonic treatment at 40 Watts per gallon. The particle levels in thefluid were measured by taking a 10 mL sample twice. The average of theseresults was used a blank. The substrate to be tested was then completelyimmersed in the water of the beaker and subjected to the same ultrasonicconditions described above. The particle levels in the fluid were thenmeasured again using the same method as above. The particle countsgenerated per surface area of the substrate were calculated as follows:

Particle Counts=[(test sample particle count−blank particle count)*500mL]/[substrate surface area]

The above procedure was repeated for three times for each substratepiece. The results presented below are for the third extraction.

Example 1

A copolymer was prepared by charging 25 g HFPOMA, 10 g BA (from AldrichChemical Company of Milwaukee, Wis.), 10 g A174 (from United ChemicalTechnologies of Bristol, N.J.), 5 g MPTS (from United ChemicalTechnologies, Inc.) and 250 g of 3M NOVEC 7200 Engineering Fluid(ethoxy-nonafluorobutane (C₄F₉OC₂H₅) from 3M Company, St. Paul, Minn.)to a flask equipped with a mixer. The solution was purged with nitrogenfor 5 minutes. Following this, 1 g of LUPEROX 26M50 initiator(tert-butyl peroxy-2-ethylhexanoate, 50% solids, from Arkema, Inc. ofPhiladelphia, Pa.) was charged to the flask. The solution was stirredunder nitrogen and heated to 65° C. for 18 hours. This solution wasdiluted to 10% polymer with 3M NOVEC 7200 Engineering Fluid. The polymersolution was catalyzed by adding KRYTOX 157 FSL (perfluoropolyalkylethercarboxylic acid from E.I. du Pont De Nemours & Company of Deepwater,N.J.) at 2% of the polymer level, i.e., about 0.2% of the overallsolution.)

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove using a pull rate of 2.54 millimeters/second (6 inches/minute). Atwo step cure was used with the first cure done at 85° C. for one hourand the second cure done at 150° C. for 1 hour. Solvent extractiontesting showed 95% cure for coatings on the aluminum coupon. The LPCextraction results on for these coatings are presented in Table 1.

Example 2

A copolymer was prepared by charging 30 g HFPOMA, 5 g BA, 10 g Al 74, 5g MPTS and 250 g of 3M NOVEC 7200 Engineering Fluid to a flask equippedwith a mixer. The solution was purged with nitrogen for 5 minutes.Following this, 1 g of LUPEROX 26M50 initiator was charged to the flask.The solution was stirred under nitrogen and heated to 65° C. for 18hours. This solution was diluted to 10% polymer with 3M NOVEC 7200Engineering Fluid. The polymer solution was catalyzed by adding KRYTOX157 FSL at 2% of the polymer level, about 0.2% of the overall solution.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove using a pull rate of 2.54 millimeters/second (6 inches/minute). Atwo step cure was used with the first cure done at 85° C. for one hourand the second cure done at 150° C. for 1 hour. Solvent extractiontesting showed 86% cure for coatings. The LPC extraction results on forthese coatings are presented in Table 1.

Comparative Example 1

A copolymer was prepared by charging 35 g HFPOMA, 10 g A174, 5 g MPTSand 250 g of 3M™ NOVEC 7200 Engineering Fluid to a flask equipped with amixer. The solution was purged with nitrogen for 5 minutes. Followingthis, 1 g of LUPEROX 26M50 initiator was charged to the flask. Thesolution was stirred under nitrogen and heated to 65° C. for 18 hours.This solution was diluted to 10% polymer with 3M NOVEC 7200 EngineeringFluid. The polymer solution was catalyzed by adding KRYTOX 157 FSL at 2%of the polymer level, i.e., about 0.2% of the overall solution.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove using a pull rate of 2.54 millimeters/second (6 inches/minute). Atwo step cure was used with the first cure done at 85° C. for one hourand the second cure done at 150° C. for 1 hour. Solvent extractiontesting showed 100% cure for coatings. The LPC extraction results forthese coatings are presented in Table 1.

TABLE 1* Substrate Al 5052 H32 Particle Count** % Particle ReductionControl*** 325,612 — Example 1 12,206 96% Example 2 8,864 97%Comparative Example 1 22,498 93% *Results are average of 5 samples**Number of particles >0.3μ per cm² of substrate ***Control samples werealuminum coupons with no coating

Analysis of the data in Table 1 showed Example 1 and Example 2 to have astatistically significant improvement in particle suppression overComparative Example 1.

Example 3

A copolymer was prepared by charging 15 g FBSEA, 26 g BA, 4.5 g A174,1.5 g MPTS, 3.0 g CN973J75 (from Sartomer Company, Inc. of Exton, Pa.),100 g 3M™ NOVEC 7200 Engineering Fluid, and 100 g ethyl acetate (productnumber EX0241 from EMD Chemicals, Inc. of Gibbstown, N.J.) to a flaskequipped with a mixer. The solution was purged with nitrogen for 5minutes. Following this, 0.5 g of VAZO 67 (from DuPont) was charged toflask. The solution was stirred under nitrogen and was heated to 65° C.for 16 hours. The solution was diluted to 10% polymer with a 50/50 blendby mass of 3M™ NOVEC 7200 Engineering Fluid and ethyl acetate. Thepolymer solution was catalyzed by adding KRYTOX 157 FSL at 3% of thepolymer level, i.e., about 0.3% of the overall solution.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 2.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 2.54 millimeters/second (6inches/minute). A two step cure was used with the first cure done at 85°C. for one hour and the second cure done at 150° C. for 1 hour. Solventextraction testing showed 79% cure on aluminum and 88% cure on stainlesssteel. The LPC extraction testing for this coating is presented in Table2.

Example 4

A copolymer was prepared by charging 12 g FBSEA, 26 g BA, 4.5 g A174,1.5 g MPTS, 6.0 g CN973J75, 100 g 3M NOVEC 7200 Engineering Fluid, and100 g ethyl acetate to a flask equipped with a mixer. The solution waspurged with nitrogen for 5 minutes. Following this, 0.5 g of VAZO 67 wascharged to flask. The solution was stirred under nitrogen and was heatedto 65° C. for 16 hours. The solution was diluted to 10% polymer with a50/50 blend by mass of 3M™ NOVEC 7200 Engineering Fluid and ethylacetate. The polymer solution was catalyzed by adding KRYTOX 157 FSL at3% of the polymer level, i.e., about 0.3% of the overall solution.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 2.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 2.54 millimeters/second (6inches/minute). A two step cure was used with the first cure done at 85°C. for one hour and the second cure done at 150° C. for 1 hour. Solventextraction testing showed 78% cure on aluminum and 92% cure on stainlesssteel. The LPC extraction testing for this coating is presented in Table2.

TABLE 2* Substrate Al5052 H32 SS304 Particle % Particle Particle %Particle Count** Reduction Count** Reduction Control*** 240,610 —150,520 — Example 3 11,671 95% 1.826 99% Example 4 13,297 94% 962 99%*Results are from a single sample **Number of particles >0.3μ per cm² ofsubstrate ***Control samples were coupons with no coating

Example 5

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 18 g A174, 6g MPTS, 2 g AA (from Alfa Aesar of Heysham, Lancashire LA3 2XY UnitedKingdom), 1 g 1-butyl peroctoate (LUPEROX 26, 100% active ingredient)(from Atofina of Philadelphia, Pa.), and 500 g 3M NOVEC 7200 EngineeringFluid to a flask under positive nitrogen pressure. The solution wasstirred under nitrogen and was heated to 70° C. for 18 hours. Thesolution was diluted to 10% polymer by mass with 3M NOVEC 7200Engineering Fluid.

A15052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 97% cure on aluminum and 100% cure onstainless steel. The LPC extraction testing for this coating ispresented in Table 3.

Example 6

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 20 g A174, 4g MPTS, 2 g mercaptoproprionic acid (from Aldrich of Milwaukee, Wis.), 1g t-butyl peroctoate (100%) and 500 g 3M NOVEC 7200 Engineering Fluid toa flask under positive nitrogen pressure. The solution was stirred undernitrogen and was heated to 70° C. for 18 hours. The solution was dilutedto 10% polymer by mass with 3M NOVEC 7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 93% cure on aluminum and 95% cure on stainlesssteel. The LPC extraction testing for this coating is presented in Table3.

Example 7

A copolymer was prepared by charging 54 g FBSEA, 20 g BA, 18 g A174, 6 gMPTS, 2 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC7200 Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M™ NOVEC7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 95% cure on aluminum and 100% cure onstainless steel. The LPC extraction testing for this coating ispresented in Table 3.

Example 8

A copolymer was prepared by charging 54 g FBSEMA, 20 g BA, 18 g A174, 6g MPTS, 2 g AA, 1 g t-butyl peroctoate (LUPEROX 26), 450 g 3M NOVEC 7200Engineering Fluid and 50 g of ethyl acetate to a flask under positivenitrogen pressure. The solution was stirred under nitrogen and washeated to 70° C. for 18 hours. The solution was diluted to 10% polymerby mass with 3M NOVEC 7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 100% cure on aluminum and 100% cure onstainless steel. The LPC extraction testing for this coating ispresented in Table 3.

Example 9

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 19 g A174, 6g MPTS, 1 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC7200 Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M NOVEC7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 90% cure on aluminum and 92% cure on stainlesssteel. The LPC extraction testing for this coating is presented in Table3.

Example 10

A copolymer was prepared by charging 54 g PFPHMA, 20 g EHA (fromAldrich), 18 g A174, 6 g MPTS, 2 g AA, 1 g t-butyl peroctoate (LUPEROX26), and 500 g 3M NOVEC 7200 Engineering Fluid to a flask under positivenitrogen pressure. The solution was stirred under nitrogen and washeated to 70° C. for 18 hours. The solution was diluted to 10% polymerby mass with 3M NOVEC 7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 100% cure on aluminum and 97% cure onstainless steel. The LPC extraction testing for this coating ispresented in Table 3.

Example 11

A copolymer was prepared by charging 54 g PFPHMA, 20 g IOA (fromAldrich), 18 g A174, 6 g MPTS, 2 g AA, 1 g t-butyl peroctoate (LUPEROX26), and 500 g 3M NOVEC 7200 Engineering Fluid to a flask under positivenitrogen pressure. The solution was stirred under nitrogen and washeated to 70° C. for 18 hours. The solution was diluted to 10% polymerby mass with 3M NOVEC 7200 Engineering Fluid.

Al5052 H32 and SS304 test coupons were cleaned by Cleaning Method 1.These coupons were then coated with the polymer solution using themethod described above using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 98% cure on aluminum and 100% cure onstainless steel. The LPC extraction testing for this coating ispresented in Table 3.

TABLE 3* Substrate Al5052 H32 SS304 Particle % Particle Particle %Particle Count** Reduction Count** Reduction Control*** 309,063 —148,912 — Example 5 43,986 86% 8,709 94% Example 6 16,330 95% 4,922 97%Example 7 26,184 92% 6,436 96% Example 8 28,135 91% 2,775 98% Example 917,801 94% 4,196 97% Example 10 28,222 91% 3,472 98% Example 11 10,62197% 1,673 99% *Results are from a single sample **Number ofparticles >0.3μ per cm² of substrate ***Control samples were couponswith no coating

Comparative Example 2

A copolymer was prepared by charging 54 g PFPHMA, 20 g MMA (from Rohmand Haas of Philadelphia, Pa.), 19 g A174, 6 g MPTS, 1 g AA, 1 g t-butylperoctoate (LUPEROX 26), and 500 g 3M NOVEC 7200 Engineering Fluid to aflask under positive nitrogen pressure. The solution was stirred undernitrogen and was heated to 70° C. for 18 hours. The solution was dilutedto 10% polymer by mass with 3M NOVEC 7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 98% cure. The LPC extraction testing for thiscoating is presented in Table 4.

Comparative Example 3

A copolymer was prepared by charging 54 g FBSEA, 20 g MMA, 19 g A174, 6g MPTS, 1 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC™7200 Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M NOVEC7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 94% cure. The LPC extraction testing for thiscoating is presented in Table 4.

Example 12

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 19 g A174, 6g MPTS, 1 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC7200 Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M NOVEC7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour.

Solvent extraction testing showed 86% cure. The LPC extraction testingfor this coating is presented in Table 4.

Example 13

A copolymer was prepared by charging 54 g FBSEA, 20 gBuMA (from LuciteInternational of Southampton SO14 3BP, United Kingdom ), 19 g A174, 6 gMPTS, 1 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC7200 Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M™ NOVEC7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour.

Solvent extraction testing showed 89% cure. The LPC extraction testingfor this coating is presented in Table 4.

Example 14

A copolymer was prepared by charging 54 g PFPHMA, 20 g BuMA, 19 g A174,6 g MPTS, 1 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3MNOVEC 7200 Engineering Fluid to a flask under positive nitrogenpressure. The solution was stirred under nitrogen and was heated to 70°C. for 18 hours. The solution was diluted to 10% polymer by mass with3M™ NOVEC 7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 120° C. for 1 hour. Solventextraction testing showed 89% cure. The LPC extraction testing for thiscoating is presented in Table 4.

TABLE 4* Substrate Al 5052 H32 Particle Count** % Particle ReductionControl*** 287,684 — Example 12 17,567 94% Comparative Example 2 57,86680% Comparative Example 3 83,810 71% Example 13 41,712 86% Example 1421,729 92% *Results are average of 3 samples, with the exception ofExample 12 which is the average of 2 samples. **Number ofparticles >0.3μ per cm² of substrate ***Control samples were aluminumcoupons with no coating

Comparative Example 4

A copolymer was prepared by charging 54 g PFPHMA, 20 g BuMA, 19 g A174,6 g MPTS, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3M NOVEC 7200Engineering Fluid to a flask under positive nitrogen pressure. Thesolution was stirred under nitrogen and was heated to 70° C. for 18hours. The solution was diluted to 10% polymer by mass with 3M™ NOVEC7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The coated coupons were heated at 120° C. for 1 hour.Solvent extraction testing showed 0% cure.

Example 15

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 19.5 g A174,6 g MPTS, 0.5 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3MNOVEC 7200 Engineering Fluid to a flask under positive nitrogenpressure. The solution was stirred under nitrogen and was heated to 70°C. for 18 hours. The solution was diluted to 10% polymer by mass with 3MNOVEC 7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). Three types of cures were run. The solvent extractiondata is presented in Table 5.

Example 16

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 19.7 g A174,6 g MPTS, 0.3 g AA, 1 g t-butyl peroctoate (LUPEROX 26), and 500 g 3MNOVEC 7200 Engineering Fluid to a flask under positive nitrogenpressure. The solution was stirred under nitrogen and was heated to 70°C. for 18 hours. The solution was diluted to 10% polymer by mass with3M™ NOVEC 7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). Three types of cures were run. The solvent extractiondata is presented in Table 5.

TABLE 5* Substrate Al 5052 H32 Cure Conditions Percent Cure Example 15120° C., 1 hour 73% 120° C., 3 hours 81% 150° C., 1 hour 100% Example 16120° C., 1 hour 41% 120° C., 3 hours 71% 150° C., 1 hour 92% *Resultsare average of 3 samples

Example 17

A copolymer was prepared by charging 54 g PFPHMA, 20 g BA, 19.5 g A174,6 g MPTS, 0.5 g AA, 0.22 g of polymerizable dye AD-4 (U.S. Pat. No.6,894,105 (Parent et al.), Column 9 and 22 line 44), 2 g t-butylperoctoate (LUPEROX 26), and 500 g 3M NOVEC 7200 Engineering Fluid to aflask under positive nitrogen pressure. The solution was stirred undernitrogen and was heated to 70° C. for 18 hours. The solution wasfiltered through a 0.1 micron nylon filter and was diluted to 10%polymer by mass with 3M™ NOVEC 7200 Engineering Fluid.

Al5052 H32 test coupons were cleaned by Cleaning Method 1. These couponswere then coated with the polymer solution using the method describedabove with using a pull rate of 4.66 millimeters/second (11inches/minute). The cure was done at 150° C. for 1 hour.

Solvent extraction testing showed 92% cure. The LPC extraction testingfor this coating is presented in Table 6.

TABLE 6* Substrate Al 5052 H32 Particle Count** % Particle ReductionControl*** 386,800 — Example 12 4,900 99% *Results are average of 3samples **Number of particles >0.3μ per cm² of substrate ***Controlsamples were aluminum coupons with no coating

Various modifications and alterations to this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention. It should be understood that thisinvention is not intended to be unduly limited by the illustrativeembodiments and examples set forth herein and that such examples andembodiments are presented by way of example only with the scope of theinvention intended to be limited only by the claims set forth herein asfollows.

1. A substrate comprising a coating on at least a portion of saidsubstrate wherein said coating comprises a fluorinated acrylate randomcopolymer having the following general formula:XA_(w)B_(x)C_(y)D_(z)T where X is the initiator residue or hydrogen, Arepresents units derived from one or more divalent fluorochemicalacrylate monomers, B represents units derived from one or more divalentacrylate monomers with a functional group, C represents units derivedfrom one or more non-fluorinated divalent acrylate monomers with ahydrocarbon group, D represents units derived from one or morecuratives, T represents a functional terminal group or X defined asabove, w is an integer from 1 up to about 200, x is an integer from 1 upto about 300, y is an integer from 1 up to about 100, and z is aninteger from 0 up to about 30, and wherein C is selected from the groupconsisting of monomers whose homopolymer has a glass transitiontemperature of less than or equal to 20° C.
 2. The substrate of claim 1wherein A is a unit derived from a monomer selected from the groupconsisting ofR^(f)QOC(═O)C(R)═CH₂ where R^(f) is a perfluoroalkyl orperfluoropolyether group having 1 to 30 carbon atoms, Q is a divalentlinking group selected from the group consisting of —(CH₂)_(n)—,—(CH₂)_(n)— SO₂N(R′)—, and —(CH₂)_(n)N(R″)C(═O)—, where R′ is—C_(n)H_((2n+1)), n is an integer from 1 to 6, and R″ is hydrogen orCH₃.
 3. The substrate of claim 1 wherein B is a unit derived from asilane-containing acrylic monomer.
 4. The substrate of claim 3 wherein Bis a unit derived from 3-trimethoxysilane propyl methacrylate.
 5. Thesubstrate of claim 1 wherein C is a unit derived from a monomer selectedfrom the group consisting of butyl acrylate, butyl methacrylate,iso-octyl acrylate, 2-(ethyl)-hexyl acrylate, and urethane acrylates. 6.The substrate of claim 1 wherein D is a unit derived from an acidiccurative.
 7. The substrate of claim 6 wherein the acidic curativecomprises acidic acid.
 8. The substrate of claim 1 wherein T is a unitderived from a monomer comprising a silane-containing mercaptan.
 9. Thesubstrate of claim 8 wherein T is a unit derived from 3-mercaptopropyltrimethoxysilane.
 10. The substrate of claim 1 wherein the numberaverage molecular weight (M_(w)) of said copolymer is from about 500 toabout 50,000.
 11. The substrate of claim 1 wherein the ratio z:(x+1) isfrom 0 to less than about 0.3.
 12. The substrate of claim 1 wherein theratio of y:w is greater than 0 and less than
 7. 13. The substrate ofclaim 1 wherein the ratio of (w+y):x is greater than 1 and less than 20.14. The substrate of claim 1 wherein said substrate is a hard disk driveassembly comprising at least one head associated with a disk surface forstoring computer data magnetically on the disk.
 15. The substrate ofclaim 1 wherein the copolymer further comprises a unit derived from oneor more (meth)acrylate functional dyes.
 16. A method of reducingparticulate contamination comprising: providing at least one of a harddisk drive assembly, a MEMS device, a process equipment for electronicsor a printed circuit card assembly; and applying a coating on at least aportion of the assembly of at least one of a hard disk drive assembly, aMEMS device, a process equipment for electronics or a printed circuitcard assembly, wherein the coating comprises a fluorinated acrylaterandom copolymer having the following general formula:XA_(a)B_(b)C_(c)D_(d)T_(e) where X is the initiator residue or hydrogen,A represents units derived from one or more divalent fluorochemicalacrylate monomers, B represents units derived from one or more divalentacrylate monomers with a functional group, C represents units derivedfrom one or more non-fluorinated divalent acrylate monomers with ahydrocarbon group, D represents units derived from one or morecuratives, T represents a functional terminal group or X defined asabove, a+b+c+d+e=1, 0.20≦a≦0.90, 0.05≦b≦0.25, 0.05≦c≦0.65,0.0005≦d≦0.03, and 0.0025≦e≦0.20, wherein a, b, c, d, and e are weightpercentages of A, B, C, D, and T, respectively, and wherein C isselected from the group consisting of monomers whose homopolymer has aglass transition temperature of less than or equal to 20° C.
 17. Themethod of claim 16 wherein, 0.40≦a≦0.80 and 0.05≦c≦0.25.
 18. The methodof claim 16 wherein the hard disk assembly comprises at least onecomponent selected from spacers, disk clamps, e-blocks, cover plates,base plates, microactuators, sliders, voice coils, or voice coil plates.19. The method of claim 16 wherein the copolymer further comprises aunit derived from one or more (meth)acrylate functional dyes.